Propylene In Presence Research Articles

Hydrates production with gaseous CO2/C3H8 and CH4/C3H8 (90/10 vol%) mixtures and definition of the role of propane during CO2/CH4 replacement processes

Within the range of temperatures suitable for CO2/CH4 replacement, propane can form hydrates at widely milder conditions than those required for methane and carbon dioxide hydrates. Recent studies proved that the addition of minor quantities of propane to carbon dioxide strongly enhances replacement process, both in terms of methane recovery and carbon dioxide storage. At the same time, the capture of propane remains limited, even if the thermodynamic conditions are widely suitable for its capture. This study experimentally provided a coherent explanation of such a process. Hydrates were formed and dissociated on a lab-scale reactor with binary mixtures containing 90 vol% of CO2/CH4 and 10 vol% of C3H8; the results were compared with the phase equilibrium conditions of the pure species, obtained with the same procedure. The promoting/inhibiting effect of propane on the forming system was quantified and explained in terms of typology of hydrate structure formed and cage occupancy. Based on the results achieved in this study, the replacement mechanism, in presence of propane, was finally characterized and compared with the results obtained when replacement was carried out with the same procedure but with pure carbon dioxide and CO2/N2 mixtures.

Enhanced Solubility and Miscibility of CO2-Oil Mixture in the Presence of Propane under Reservoir Conditions to Improve Recovery Efficiency

The existence of propane (C3H8) in a CO2-oil mixture has great potential for increasing CO2 solubility and decreasing minimum miscibility pressure (MMP). In this study, the enhanced solubility, reduced viscosity, and lowered MMP of CO2-saturated crude oil in the presence of various amounts of C3H8 have been systematically examined at the reservoir conditions. Experimentally, a piston-equipped pressure/volume/temperature (PVT) cell is first validated by accurately reproducing the bubble-point pressures of the pure component of C3H8 at temperatures of 30, 40, and 50 °C with both continuous and stepwise depressurization methods. The validated cell is well utilized to measure the saturation pressures of the CO2-C3H8-oil systems by identifying the turning point on a P-V diagram at a given temperature. Accordingly, the gas solubilities of a CO2, C3H8, and CO2-C3H8 mixture in crude oil at pressures up to 1600 psi and a temperature range of 25–50 °C are measured. In addition, the viscosity of gas-saturated crude oil in a single liquid phase is measured using an in-line viscometer, where the pressure is maintained to be higher than its saturation pressure. Theoretically, a modified Peng–Robinson equation of state (PR EOS) is utilized as the primary thermodynamic model in this work. The crude oil is characterized as both a single and multiple pseudo-component(s). An exponential distribution function, together with a logarithm-type lumping method, is applied to characterize the crude oil. Two linear binary interaction parameters (BIP) correlations have been developed for CO2-oil binaries and C3H8-oil binaries to accurately reproduce the measured saturation pressures. Moreover, the MMPs of the CO2-oil mixture in the presence and absence of C3H8 have been determined with the assistance of the tie-line method. It has been found that the developed mathematical model can accurately calculate the saturation pressures of C3H8 and/or CO2-oil systems with an absolute average relative deviation (AARD) of 2.39% for 12 feed experiments. Compared to CO2, it is demonstrated that C3H8 is more soluble in the crude oil at the given pressure and temperature. The viscosity of gas-saturated crude oil can decrease from 9.50 cP to 1.89 cP and the averaged MMP from 1490 psi to 1160 psi at 50 °C with the addition of an average 16.02 mol% C3H8 in the CO2-oil mixture.

Kinetics of hydrate formation by CO2 and mixture of CO2–C3H8 in concentrated NaCl solution: Effect of impellers

Hydrate-based desalination (HBD) can apply directly to high-salinity water produced with crude oils and gases. For HBD technology to be commercialized, the slow kinetics of hydrate formation must be overcome. This study investigates the effects of type, diameter, number and clearance of impellers on kinetics, i.e. nucleation and growth, of hydrates of pure CO2 and mixture of CO2–C3H8 in a stirred vessel. Concentrated saline solution (8 wt%) was applied to form hydrates at constant temperatures (271.15–279.15 K) and pressures (1.73–3.6 MPa). Single pitched blade (PB) and straight blade (SB) impellers and also dual combinations of them were applied. With both SB and PB impellers at single mode, lower clearance improved nucleation rates (lower induction times) and higher clearance improved growth rates. The growth rate with SB was higher than that with PB under similar conditions, showing that radial flow is in favor of growth rate. With dual combination of PB and SB, higher nucleation and growth rates were observed compared to single impellers. The presence of PB in dual configuration influenced only the nucleation rate. Using a large diameter SB impeller, resulted in higher growth rate and gas consumption in dual mode. The results with CO2–C3H8 mixture were the same as pure CO2. Due to the promoting effect of propane on nucleation and growth rates, the effects of variation in propeller characteristics became minor in the presence of propane.

Excellent hydrocarbon tolerance of CeO2-WO3-SnO2 oxide catalyst for the NH3-SCR of NO

The tolerance of NH3-SCR catalysts towards hydrocarbon compounds (HCs) is very important for their practical application on diesel vehicles. In this study, the HC resistance of CeWSnOx, V2O5-WO3/TiO2 and Cu-SSZ-13 catalysts was systematically investigated using propene, toluene and n-pentane as model HCs. Experimental results suggested that the fresh and hydrothermally aged CeWSnOx showed much better HC tolerance than the Cu-SSZ-13 and V2O5-WO3/TiO2. This property mainly originated from the strong HC oxidation capacity of the CeWSnOx due to Sn introduction, which significantly inhibited side reactions, including the HC ammoxidation and the carbon deposition reactions. In contrast, an undesired HC ammoxidation reaction occurred at medium temperatures over the Cu-SSZ-13 and at medium-high temperatures over V2O5-WO3/TiO2, especially in the presence of propene, accompanied by the emission of toxic HCN gas. The high HC tolerance of CeWSnOx gives it promise for application on heavy-duty diesel after-treatment systems in the future, especially those with the SCR-on-DPF or cc-SCR configuration.

The study on Cu-ZK-5 catalyst of copper content regulation and anti-propylene poisoning mechanism in NH3-SCR reaction

Cu-ZK-5 catalysts have been attempted to utilize as NH3-SCR because they have small pores and eight-membered ring structures. In this work, Cu-ZK-5 catalysts with different copper contents were investigated. It was found that the Cu7.55-ZK-5 catalyst showed excellent activity and resistance to propylene poisoning for NH3-SCR. When the copper content is too low, the number of active copper species is less, and the activity is poor. When the copper content is too high, CuOx species will be generated to destroy the structure of the molecular sieve and affect the activity, which manifested that the optimal copper loading of Cu-ZK-5 catalyst possesses more Cu2+ species improving the activity for NH3-SCR. Furthermore, the presence of propylene on Cu7.55-ZK-5 catalyst had little impact on the low-temperature catalytic performance and exhibited excellent propylene resistance at medium and high temperatures. The influence on the low-temperature catalytic performance of the Cu-ZK-5 catalyst is mainly since C3H6 has competitive adsorption with NO on the surface of Cu-ZK-5, which may be the main reason for slightly reducing the NOx conversion of Cu-ZK-5 catalyst.

Effect of propylene in feedstock on the coking behavior of PtSnK/Al2O3 catalyst of propane dehydrogenation

The dehydrogenation of propane was carried out with feed gas containing different proportions of propylene, and the coking behavior of Pt-based catalyst under propene-rich condition was investigated. The results show that the presence of propylene in the raw material accelerates the rate of coke deposition, shortens the time of dynamic equilibrium of coke deposition on the support, and promotes the formation of coke on the surface area of the active phase and the subsequent graphitization. At the same time, the increase the amount of unsaturated aliphatic compounds, thus promoting the generation of aromatic carbon and graphitized carbon, while the catalyst structure is not destroyed. In the process of propane dehydrogenation, the coke “Peak I” appears on the surface of the active phase, and the “Peak II” moves to the high-temperature region, when the propylene content increase to 1.5%. With the alkene content increasing to 3.0%, Peak I and Peak II merge into a larger peak, the area of which increases significantly. When the coke content exceeds 10.26%, the graphitization degree of the catalyst becomes higher and higher. The increase of the propylene content accelerates the saturation process of the coke holding capacity of the carrier, meaning the increasing amount of coke deposit under the same reaction time.

The Study of C3H6 Impact on Selective Catalytic Reduction by Ammonia (NH3-SCR) Performance over Cu-SAPO-34 Catalysts

In present work, the catalytic performance of Cu-SAPO-34 catalysts with or without propylene during the NH3-SCR process was conducted, and it was found that the de-NOx activity decreased during low temperature ranges (<350 °C), but obviously improved within the range of high temperatures (>350 °C) in the presence of propylene. The XRD, BET, TG, NH3-TPD, NOx-TPD, in situ DRIFTS and gas-switch experiments were performed to explore the propylene effect on the structure and performance of Cu-SAPO-34 catalysts. The bulk characterization and TG results revealed that neither coke deposition nor the variation of structure and physical properties of catalysts were observed after C3H6 treatment. Generally speaking, at the low temperatures (<350 °C), active Cu2+ species could be occupied by propylene, which inhibited the adsorption and oxidation of NOx species, confining the SCR reaction rate and causing the deactivation of Cu-SAPO-34 catalysts. However, with the increase of reaction temperatures, the occupied Cu2+ sites would be recovered and sequentially participate into the NH3-SCR reaction. Additionally, C3H6-SCR reaction also showed the synergetic contribution to the improvement of NOx conversion at high temperature (>350 °C).

Supercritical Water Oxidation of 3-Methylpyridine with Propylene Glycol

The destruction of 3-methylpyridine by supercritical water oxidation (SCWO) using propylene glycol (PG) and isopropyl alcohol (IPA) as co-fuels in a plug flow reactor was carried out. Hydrogen peroxide was the oxygen source. All the experiments were carried out at 25 MPa and a range of temperatures from 425-525 ºC. The residence times range from 6 s to 14 s. Results were presented in terms of total organic carbon (TOC) as a function of time with various process parameters. The findings support the positive effect that propylene glycol has on the destruction of 3-methylpyridine, where TOC removal is ≥ 97.5% at 525 ºC and 14 s. The maximum TOC removal efficiency is 93% at 425 ºC, 14 s, and the [propylene glycol]/[3-methylpyridine]o ratio of 3. The removal efficiency of nitrogen in the presence of propylene glycol reaches 89% at 525 ºC and 10 s. The oxidant ratio also has a positive effect on the removal of TOC in the three systems. Addition of propylene glycol causes a significant development in the ratio at 425 ºC, more so than when isopropyl alcohol was added. This is due to two hydroxyl groups in propylene glycol oxidation that enhance the reaction by generating various free radicals.

A novel approach for the estimation of the Sanchez-Lacombe interaction parameters for the solubility of ternary polyolefins systems

The total solubility of ethylene in LLDPE in presence of propane, isobutane and 1-butene is measured using a gravimetric technique at 70 °C and pressures up to 5 bars. In order to overcome the lack of experimental partial solubility data in ternary systems, a novel approach for the estimation of the Sanchez-Lacombe interaction parameters is proposed. The total solubility measurements combined with the independent estimate of the compressibility factor for a mixture of gases using Peng-Robinson EoS as a second “data source” were fitted to SL EoS in order to identify its interaction parameters. This makes it possible to calculate individual component solubility data for the two penetrants in a non-ideal ternary system where the third phase is polyethylene. The observed trends were theoretically interpreted because no available data can be found in the literature for these studied systems. Good agreement was observed between the experimental overall solubility and SL EoS combined to PR EoS, with a difference of 1–4% for the overall solubilities and a maximum of 0.8% for the compressibility factor.

Studying the Stage of Nitric Oxide Desorption from the Surfaces of CuO/γ-Al2O3 Catalysts, with or without a Reducing Agent

Nitric oxide desorption from the surfaces of supported copper-containing catalysts (CuO/γ-Al2O3) as a function of temperature is studied. NO preadsorption occurs both in an inert medium of argon and in the presence of oxygen. It is shown that the presence of oxygen considerably raises the capacity of the samples with respect to NO, due to the activation of a supplementary redox mechanism. In addition, the maximum desorption temperature shifts to the region of higher temperatures. For a sample exhibiting the highest capacity with respect to NO, the desorption process is conducted using hydrogen and propane as reducing agents. Desorption with hydrogen leads to the reduction of adsorbed species at temperatures of 160–190°C. With propane, NOx desorption proceeds mostly due to the thermal degradation of adsorbed nitrogen species to NO in the temperature range of 180–250°C, as in an inert atmosphere. The contribution from reduction due to the presence of propane manifests at temperatures of 260–300°C.

An Investigation on the Performance of an Oxidation Catalyst Using Two-dimensional Simulation with Detailed Reaction Mechanism

Abstract The advent of stricter emission standards has increased the importance of aftertreatment devices and the role of numerical simulations in the evolution of better catalytic converters in order to satisfy these emission regulations. In this paper, a 2-D numerical simulation of a single channel of the monolith catalytic converter is presented by using detailed surface reaction kinetics aiming to investigate the chemical behaviour inside the converter. The model has been developed to study the conversion of carbon monoxide (CO) in the presence of propene (C3H6) for low-temperature combustion (LTC) engine application. The inhibition effect of C3H6 over a wide range of CO inlet concentrations is investigated. Considering both low and high levels of CO concentration at the inlet, the 2-D model predicted better results than their corresponding 1-D counterparts when compared with the experimental data from literature. It was also observed that C3H6 inhibition at high temperatures was significant, particularly for high concentrations of CO compared to low concentrations of CO at the inlet.

Selective hydrogen combustion in the presence of propylene and propane over Pt/A-zeolite catalysts

The behavior of selective hydrogen combustion (SHC) in the presence of propylene and propane changing with reaction temperature in a range of 100–600 °C has been investigated over the Pt catalysts supported on A-zeolites. The effect of Pt loading varying from 0.01 to 2 wt% on the catalytic SHC performance has been studied in the conditions with a feed gas molar composition of C3H8/C3H6/H2/O2 = 4/4/4/2 balanced with N2 and gas hourly space velocity of 15,000 h−1. The results show that for each Pt/3A catalyst having a different Pt loading there is a maximum of H2 conversion by combustion appearing between 300 and 400 °C, while the selectivity to comprehensive H2 conversion can maintain 100% when the temperature lower than 300 °C. Moreover, the Pt/3A catalyst with a Pt loading of 0.5 wt % performs better than the others at the temperatures higher than 300 °C. The maximal H2 combustion achieved over the 0.5 wt% Pt/3A catalyst is as high as 96.6% along with a selectivity of 100% at 300 °C, and a 92.4% H2 combustion with 98.5% selectivity can be obtained even if at 500 °C. The characterization of the catalysts reveals that the distribution of Pt atoms and the number of atoms in Pt clusters may be the key factors for giving rise to the good SHC performance. The influence of three types of A-zeolite supports on the Pt catalyzed SHC process has also been investigated. 3A zeolite is superior to 4A and 5A for supporting 0.5 wt% Pt catalyst in terms of both activity and selectivity. The lower C3H6 conversion on the 0.5 wt% Pt/3A catalyst compared to the 0.5 wt% Pt/5A may be ascribed to the insufficient sites for the C3H6 activation on the surface of Pt/3A due to the limitation of 3A channels inaccessible to C3H6. This contrarily brings about the better SHC performance on the 0.5 wt% Pt/3A catalyst.

Investigation of NO desorption from the surface of CuO/γ-Al2O3 catalysts, particularly in the presence of a reductant

The process of NO desorption from the surface of supported copper-containing catalysts CuO/ γ -Al 2 O 3 was studied in dependence on temperature. Therewith, the preliminary adsorption of NO was carried out both in an inert argon medium and in the presence of oxygen. It was shown that the presence of oxygen considerably increased the capacity of samples with respect to NO owing to the additional redox mechanism. Besides, the desorption temperature maximum shifted toward higher temperatures. For the sample with the highest capacity to NO, the desorption was performed in the presence of hydrogen or propane as a reductant. Desorption in the presence of hydrogen led to the reduction of adsorbed species at a temperature of 160–190 °C. In the presence of propane, NO x was desorbed mostly due to thermal destruction of adsorbed nitrogen species to NO in the temperature range of 180–250 °C, similar to the case of inert atmosphere. The contribution of reduction due to the presence of propane showed up at a temperature of 260–300 °C.

Numerical optimization of methane-based fuel blends under engine-relevant conditions using a multi-objective genetic algorithm

The objective of this work is to examine in a systematic way, how conflicting requirements such as maximum ignition delay time and laminar flame speed can be met by adding gaseous components to methane in order to obtain the optimal fuel blend under engine-relevant conditions. Low-dimensional models are coupled with a multi-objective optimization algorithm in order to compute optimal methane/hydrogen, methane/syngas and methane/propane/syngas blend compositions that maximize simultaneously the ignition delay time, the laminar flame speed and the Wobbe number. The non-dominated sorting genetic algorithm (NSGA-II) is used to generate a set of Pareto solutions, and the best compromise solutions are then determined by the technique for order preference by similarity to ideal solution (TOPSIS).It was found that the GRI-Mech 3.0 mechanism could not accurately predict ignition properties of methane-based fuel blends under engine-relevant conditions. The optimization results revealed that initial conditions have a significant effect on the optimal fuel blend composition. For methane/hydrogen and methane/syngas blends, pure methane was the optimal fuel at high temperatures and low equivalence ratios, while high hydrogen contents were beneficial at lower temperatures. When the ignition delay time is of higher importance, the optimal composition shifted towards higher carbon monoxide contents. Blends with higher hydrogen and syngas contents resulted in reduced ignition delay times and higher laminar flame speeds. Regarding the methane/propane/syngas blend, the presence of propane in the optimal blend was found to be more favorable than hydrogen and carbon monoxide to satisfy the objectives.

Hyperbranched polymer–silver nanohybrid induce super antibacterial activity and high performance to cotton fabric

Herein we present a novel approach for synthesis, characterization and application of a benign hyperbranched polyester amide–silver nanohybrid (Ag/HBPEA). The Ag/HBPEA is developed through three distinct steps. The first step involves amidation reaction of diethanol amine and maleic anhydride to yield AB2 monomer (adduct 1). The second step comprises reaction of adduct 1 with trimethylol propane in presence of catalyst to yield HBPEA. The third step entails reduction of silver nitrate by sodium borohydride reductant to effect in situ formation of AgNPs which are stabilized by HBPEA, leading ultimately to Ag/HBPEA nanohybrid. Both Ag/HBPEA nanohybrid and HBPEA are independently applied to cotton fabrics as per the conventional pad-dry-cure technique. To this end, through investigations into the structures of Ag/HBPEA nanohybrid and HBPEA stabilizer before and after application to cotton fabric using advanced techniques emphasize the Ag/HBPEA nanohybrid as multifunctional finishing agent rather than a super antibacterial activity of the cotton fabrics after treatment with Ag/HBPEA nanohybrid speaks of this. Current research generally addresses green chemistry because treatments involved therein are based on green basics and practices.

Hybrid catalysts with enhanced C3H6 resistance for NH3-SCR of NOx

Utilization of Fe-Beta for NH3-SCR of NOx in diesel engine applications is severely limited by hydrocarbon poisoning. In this work, a series of hybrid catalysts are prepared by mechanical mixing of zeolites and oxides, and their activity for the selective catalytic reduction of NOx with NH3 is investigated in the presence of propene. Results have shown that a catalyst prepared by mixing Fe-Beta and MnOx/CeO2 in a mass ratio of 1:1 exhibits high SCR activity. NOx conversion in the temperature range 200–400 °C has exceeded 90% at a GHSV of 80,000 h−1, with low selectivity to N2O. By the combined DRIFTS and MS measurements, the function of MnOx/CeO2 in the hybrid catalysts is discussed. This hybrid catalyst is able to convert C3H6 to intermediates containing CO and COO functionalities, thereby decreasing carbon deposition on the zeolite and reduce the competitive adsorption between C3H6 and NOx. Moreover, these intermediates react with NOx at lower temperatures than do the carbonaceous deposits on Fe-Beta, enhancing the NOx reduction activity.

Hybrid materials obtained by in situ polymerization based on polypropylene and mesoporous SBA-15 silica particles: Catalytic aspects, crystalline details and mechanical behavior

Nanocomposites based on polypropylene have been prepared by in situ polymerization of propene in presence of mesoporous SBA-15 silica. Synthetic reactions were carried out with a zirconocene catalyst under either homogenous or supported conditions, the SBA-15 particles being used as carriers, and testing the immobilization of the catalytic system by several approaches. The existence of polypropylene able to crystallize within the mesoporous channels in the resulting materials is initially figured out from the appearance of a small endothermic process on heating calorimetric experiments, located at around 100 °C. The presence of polypropylene crystallites confined within the SBA-15 mesostructure is thereafter confirmed by SAXS measurements through the intensity variation of the SBA-15 first order reflection, this change being dependent on composition. Accordingly, polypropylene chains can grow up either outside or inside the SBA-15 channels during polymerization and the mesoporous particles maintain their ordered hexagonal arrangement. Mechanical response, as deduced from indentation measurements, improves with SBA-15 incorporation (without varying the final processing temperature). Thus, stiffness increases and deformability is reduced in the nanocomposites as the SBA-15 content rises. Simultaneously, polypropylene amount within channels is enlarged. Amount of SBA-15 is, then, the most important variable.

Phase equilibria of the binary systems of fenofibrate and dense gases (carbon dioxide, propane, trifluoromethane)

The purpose of this work was to investigate phase equilibria, namely equilibrium solubility and melting point depression of fenofibrate in several dense gases (carbon dioxide, propane, trifluoromethane). The equilibrium solubility of fenofibrate in sub- and supercritical gases was measured using a static-analytical method at temperatures of 303.15 K, 323.15 K and 338.15 K in the pressure range from 0.10 MPa up to 35 MPa. In general, the solubility of fenofibrate in gas rich phase increases with increasing pressure at a constant temperature. The highest solubility of fenofibrate was observed in the presence of propane at all investigated temperatures. In addition, an empirical correlation based on Gordillo model was employed to estimate the experimental data. For determining the melting point of fenofibrate under pressured gas, a modified capillary method was applied in the pressure range from 0.10 MPa to 41 MPa. A melting point depression with a temperature minimum in the p,T - projection of the SLG line has been noticed for all of the investigated systems.

Boosting Size-Selective Hydrogen Combustion in the Presence of Propene Using Controllable Metal Clusters Encapsulated in Zeolite.

A strategy is presented for making metal clusters encapsulated inside microporous solids selectively accessible to reactant molecules by manipulating molecular sieve size and affinity for adsorbed molecules. This expands the catalytic capabilities of these materials to reactions demanding high selectivity and stability. Selective hydrogen combustion was achieved over Pt clusters encapsulated in LTA zeolite (KA, NaA, CaA) in a propene-rich mixture obtained from propane dehydrogenation, showing pore-size dependent selectivity and coking rate. Propene tended to adsorb at channels or external surfaces of zeolite, interfering the diffusion of hydrogen and oxygen. Tailoring the surface of LTA zeolite with additional alkali or alkaline earth oxides contributed to narrowing zeolite pore size and their affinity for propene. The thus-modified Pt@KA catalyst displayed excellent hydrogen combustion selectivity (98.5 %) with high activity and superior anti-coking and anti-sintering properties.

Boosting Size‐Selective Hydrogen Combustion in the Presence of Propene Using Controllable Metal Clusters Encapsulated in Zeolite

AbstractA strategy is presented for making metal clusters encapsulated inside microporous solids selectively accessible to reactant molecules by manipulating molecular sieve size and affinity for adsorbed molecules. This expands the catalytic capabilities of these materials to reactions demanding high selectivity and stability. Selective hydrogen combustion was achieved over Pt clusters encapsulated in LTA zeolite (KA, NaA, CaA) in a propene‐rich mixture obtained from propane dehydrogenation, showing pore‐size dependent selectivity and coking rate. Propene tended to adsorb at channels or external surfaces of zeolite, interfering the diffusion of hydrogen and oxygen. Tailoring the surface of LTA zeolite with additional alkali or alkaline earth oxides contributed to narrowing zeolite pore size and their affinity for propene. The thus‐modified Pt@KA catalyst displayed excellent hydrogen combustion selectivity (98.5 %) with high activity and superior anti‐coking and anti‐sintering properties.